yes they use it to get info on enemy positions
you can watch some old olofmeister demos from 2015, he was the best at it.
just put your crosshair on one side of where you expect enemies to be, shortly tap the aimkey, and you can tell from the acceleration which position your enemy is in.
it wont lock on unless you hold the button down too long.
obviously they also use it for headshots, but its basically impossible to tell the difference there. seeing when they use it through walls is easier because they have tells.
like stewie2k with his "nervous tick". all pros have certain conditions under which they are first unsure, then aim at an enemy through a wall, and then they know what to do. because its through the aimbot that they get info, by letting it move their crosshair.
this is lan safe because unlike with a wallhack you dont need to display anything on screen to get the extra info. so admins etc cant see it, cameras filming screens cant see it.
guys who have tells when they aimbot are more rare but they exist; simple, flusha, kjaerbye. flusha was super blatant on fnatic. he or his aimbot config would fuck up, and you could literally see him pull it off target and shake off the lock.
of course the cheats have become better over the years. some people say they all stopped cheating. i wonder why. no one got caught except some french guys. flusha never banned. senor vac.
i think they just became a bit less blatant and the cheats improved and they all got better at hiding it.