Im thinking of buying a spy camera for my room and need to know if I have to buy a special DVR box or if I could just use my Comcast Box with DVR?

I am looking for a video camera that i can install in my car sorta like what the police have in there vehicles ..i want it to be like a small spy camera thats not too expensive .. I appreciate your answers have a blessed day ~ Peace

I am looking for a video camera that i can install in my car sorta like what the police have in there vehicles ..i want it to be like a small spy camera thats not too expensive .. I appreciate your answers have a blessed day ~ Peace