Oh the stories I have heard from managers since we sent people to WFH during Covid! While there are some that a just as productive at home as they are in the office there were always some bad apples trying to avoid work too. The best are the ones that are part of call centers that have call monitoring software on their machines but some apparently thought that they couldn't monitor them when they were WFH. Heard stories of people logging in but never taking a call or one recently that looked like they were taking calls but would disconnect them as soon as one came in. Once the manager reviewed the call times and call recordings they got busted for intentionally disconnecting customers. Some of these same people that abused the WFH will use the "my internet is down" excuse too enough times that it becomes more of a pattern/habit and not random occurrences. Also when they are having technology "issues" a manager will ask them to share their screen with them to show them what is going on and usually the response is "oh well its not happening at this moment" so the manager will tell them to let them know when it is and for some odd reason the issue just happens to go away after that
The mouse jiggler may buy you some time if you need to look like you are online while not actually at your PC but depending on your job role I'm guessing there are probably systems or software in place that are tracking your productivity throughout the day. Several systems of record for the company I work for if you don't click on or enter something within that system within 15 minutes it times out out and forces you to log back into it again and if someone wanted to audit it I'm sure they can track all the logins and inactivity times out if needed. If you do a job that requires you to make or receive customer phone calls that stuff definitely is tracked in real time and likely screen capture software as well. A lot of this is starting to go away now because most groups have been brought back into the office in some kind of hybrid model or their department is not allowing "system issues" as an excused reason and require them to come into the office if their internet goes down or have a technology issue preventing them from doing their work they need to come in for support. Especially in 2020 and early 2021 it didn't take long to figure out which people were making up "technology issues" when you would see the same names in the problem ticket queue regularly and even go as far as replacing their device once or twice to start to see trends about who may be intentionally trying to avoid work. The threat of having to come work into the office if they can't be productive at home usually put an end to a lot of those.