I have a bit of a weird situation.
I work for a tech subsidiary of a large multinational corporation that employs across all subsidiaries and companies owned a total of around 180-200k employees.
My small company branch of <10 people shares an office building with a sister company branch of about 20 or so with whom we do not share any kind of work responsibilities. Our actual workloads are completely unrelated, with the exception of sharing an HR department. The management of their team has absolutely no power of our team beyond maybe pulling some strings behind the scenes.
The CFO of their company, for some reason, has taken it upon himself to constantly walk past and peer into my office throughout the day. I share my office with two coworkers. I didn't even really notice until my coworker pointed out that he was doing it, and told me that he had a history of complaining to our boss if we left the building early or got to work late-- even with a totally legitimate reason (including WFH which is given to us at times). My boss is frequently traveling, so the CFO must feel somehow like it's his responsibility to do this, as though we are too immature to be professional.
After my coworker pointed out that their CFO was constantly doing this, I started to notice it more and more. The glances grew longer. I would make awkward eye contact as he did it. I then started counting occurances: 10-15 per day.
This week came the real kicker. My office has two doors: one that leads to the hallway that everyone uses, which is the hallway he always stares into my office from, and the other door in my office is behind my desk and leads to a couple cubicles that are also accessible by the common hallway. This second hallway is a part of the building which typically only my team uses (we can talk to each other while the door is open, but it's usually closed while we're working). The CFO walks through my office, from my team hallway, to the common hallway, and stares at my screens as he walks through my office.
At this point, it's really getting distracting and incredibly obnoxious. Not only is it obnoxious, it's very rude and in my opinion disrespectful. This guy is typically rude, but having him walk through my office was another level of rude. It's just getting more and more obnoxious, and really beginning to stress me out. It's affecting my work because it happens at least once an hour, possibly more...How does he have time to do this? Doesn't he have work to do?
I've never had any work-performance issues, I've scored very well in my work reviews.
What can I do to stop a guy who swings some weight in my company's ladder, but has no direct control over me or my team to stop bugging me without making a huge deal? I don't have anything to hide, it's just distracting and rude, and makes me feel paranoid, even though I have nothing to hide.
One of the biggest draws to me working here was during my interview when my boss told me, "I'm not a micromanager." And he's not. This just feels like I'm being silently micromanaged by someone who isn't even in my company.
Also I feel like I should note that the nosy CFO's company is not a tech company, they are a construction company. I believe this may affect his attitude somewhat.
So I decided to get more passive-aggressively confrontational with all encounters of said CFO. I started giving very steady and deliberate eye contact with him whenever he would walk by and peer into my office. I found that the harder the eye contact, the quicker he would scurry off awkwardly. Since I started doing this, the total number of times he checks in has decreased. He'll still walk by my office fairly frequently, but I think that making it obvious that I noticed really helped the situation. If anything else comes from these interactions, I'll update here.