How can I catch my brother in action from stealing in my room to prove my point?
Set up a video camera in a teddy bear or something if you can... That's my best guess....
Borrow a hidden camera and set it up in your room.
Set up a webcam and use a program to record through the day/night.Or use a regular video camera and then afterwards just play it back on there instead of hooking it into the computer. Then you'll have evidence on video.