Blue Iris allows you to create a zone, in your case, it would be around the edge of your desk,

When an event in that zone happens, it can be used to trigger an alert or action.
https://imgur.com/a/3AZUv0p

I’m not sure how you would convert that event in to physical action, maybe you could send an email to a mobile that has a really loud notification and vibration.

I have used Remootio in the past to manage gate, it can send a trigger to a relay. You could use it to trigger a relay attached to a motor that spins a flyswatter or something like that. It would be a bit of trial and error, but its likely one of the easier options to try rather than learning Arduino coding and whatnot.

No, a regular person does not have access to the required systems or skills to do what you ask.