Am I Allowed To Put A Security Cam Inside My Mom's House?

USA, Illinois.

The very short tldr is that I live with my Mom, and my brother has moved back in with us. He regularly hits me, threatens me with knives, and tries to hurt my dog. Again, very short tldr of a big situation. The issue is that my Mom doesn't believe me, the only place my brother and I see each other is in the kitchen, so I wanted to get like one of those ring security cameras for it to place secretly.

He acts nice when he thinks he might be on camera, or when my Mom is around. So there's no way for me to gather proof other than this. It's my Mom's house, so I'm unsure if any evidence I gather will be usable since it's not technically my own. If that's not allowed does anyone know of a legal way to potentially gather evidence there? Voice recording...basically anything? Please help