In Belgium, it is legally required to put a sign up if you have cameras, you can’t point them at a place including public properties IIRC, and you can force them via the local government to move the camera if they are pointing at your property (at least in theory).

Lasers. Blue lasers are what you can do. reddit.com/…/what_is_this_person_doing_to_my_came… (hate to link to reddit but it is a good demo)