I think you should be upfront abut what theyre doing, because they are in the wrong. I don't think it's right, because its a violation of your privacy. I would confront them about it, and do what it takes and try to get your point across. At the same time, I would highly recommend also trying to gain their trust. 

I think you should just ask them why they put a camera in your room. Ask if they are willing to take it out and explain to them how the camera made you feel (like if it felt invasive, like they didn't trust you, made you uncomfortable, etc.).