help someone is going through my belongings when i’m not looking

I 22f have a connective tissue disease so i’m prescribed mild pain killers for it. however, twice now my meds have gone missing. i’m not sure who it is. i live with two people but i don’t believe its either of them. anywho i need a small camera to set up in my room to catch them. i don’t know anything about tech and i don’t have a lot of money. however if i have to spend a good bit to get something decent and usable then ill do it. please help. thank you