They probably use such software, but it shouldn't matter either way if you only do work-appropriate activities on your computer.
Is Employee Monitoring Software in Common Use?
The term "Employee Monitoring Software" is quite broad, as it can range from a simple website blocklist to recording the user's desktop for later review. Wikipedia has a list of types of employee monitoring software.
I have seen an IT administrator use the remote desktop viewer, but they mentioned that it was rare and used more for troubleshooting than checking employee behavior. On the other hand, the last several places I worked had an internet filter in place to prevent employees from accessing inappropriate sites (social media, gambling, adult content, malware, etc). That filter software would also generate a report of which employees were attempting to access the sites and how frequently they were bumping into the filter.
A lawyer at my previous company mentioned that the internet filtering software was required because if Employee A complained about Employee B looking at adult content on a work computer, the company could be liable for not preventing Employee B from accessing such content. I took that to mean that most large companies in the United States will probably have internet filters in place to avoid similar liability.
It was also understood at all of my previous companies that while no one was constantly reading everyone's emails, the company had mechanisms to look at a specific user's messages if they needed/wanted to do so.
Does Company X Use Monitoring Software?
The places I would check would be:
- The employment contract, as there is usually a section about "proper use of company electronic resources" or something like that which mentions what you can and cannot do on the network.
- The IT staff, as they are usually the ones who configure and maintain such software. However, they may not be allowed to tell you the specifics of how you are being monitored, depending on the company's policies.
- HR, as they are usually the ones to determine how the company's policies should be enforced.
With that said, it may be legal in your area for the employer to monitor you without telling you ahead of time, so there may be no way to know. You probably want to consult a lawyer in your area to see if that is the case.
How should adjust my behavior?
You should be safe if you always follow your company's guidelines. If your company allows you to use their computers for personal business during lunch or after your work is done, then feel free to do so. If your company says that work computers are only for work-related activities and cannot be used for any non-work stuff, then follow that and do your personal activities on your personal computer at home. If you are not sure what your company's policy is or if your planned usage meets that policy, ask your supervisor or ask HR.
If there are no company guidelines, the safest approach would be to only do work-related activities on the work computer so that if the issue comes up later on, you can defend your usage by explaining how those activities are reasonably related to the business. For example, I was asked why I was trying to visit some blogging site at such and such a time. I explained that I was googling an obscure error message while debugging an issue, and most of the google results linked back to a blog post of someone that had gone through the same issue and written up how they had solved the issue. They looked at the site in question, saw that it was what I described, and that was the end of it. Had I not had a valid business reason for trying to visit that site, I imagine that it would have been a bigger issue.
Even if your company does not use any sort of employee monitoring software, there are other ways that the company could find out if an employee has been doing something not related to work on a work computer:
- Websites can leave all sorts of junk lying around the computer long after the browser is closed. It could be as harmless as cookies/cache/browser history or as harmful as a virus, trojan, or other malware.
- Other employees, managers, or visitors could glance at an employee's screen as they walk by and notice that something more exciting than excel spreadsheets is going on.
- A computer might not be performing properly and IT might find non-sanctioned software running on it as they troubleshoot it.
There might be even more ways that inappropriate usage is detected at a particular company, but the point is not to list out everything that can get a user in trouble.
The point is, as keshlam points out in a comment, the only safe approach is to always conduct yourself professionally as if you are always being monitored.