In addition to telling the employees that they should be on call at their home during paid time, you can also inform them that an internal investigation will be carried out regarding employees who get arrested for breaking the quarantine, and appropriate disciplinary actions will be applied to them if they are found to have knowingly damaged the business by disobeying the order to stay at home during paid time.
You will need to actually conduct an investigation and check with a lawyer before applying a disciplinary action to an employee (especially before firing them). But, depending on circumstances, this may not be an empty threat: in some cases you will be able to reprimand or dismiss an employee for deliberately getting prison time. If there's solid proof that illegal activities were carried while the employee was on the clock, the risk for such an employee to be dismissed for misconduct is very high.
Hopefully even a remote possibility to get a prison sentence and losing their job will be enough to convince most people to respect the rules.