3 year olds.

How do i keep my 3 year old son in his room. He wakes us in the middle of the night and gets into the fridge. He firgured it out after we done bought a lock for the fridge. He will climb up on the counters and get food out of the cabinet's he will turn the tv on in the living room dig in drawers, he just gets into everything its all the food out the fridge. I have a door knob lock on the back of his door, and i was using the monitor on him while i kepted the door shut, he knows how to get that off and he knows how to open the baby gate i have up also. Hes just to smart I have no idea what to do. 😩