It depends where you want the camera(s), how many cameras, where you have power etc and do you want wired cameras or wireless - bearing in mind that 'wireless' cameras still need a wire to a power socket.
Sounds like you just need some sort of CCTV recording system?
I have this set up from Swann -
https://www.swann.com/uk/swnvk-485kh2. It happens to be 'wireless' between cameras and the HDD recorder but wired versions are also available. It records direct to the HDD - it
can be connected to your router or just run as a stand alone recording system, hooked up your TV. It can be set to record when it senses motion, either in the whole field of view or within specified areas, or on a timer, or both. It came with 2 cameras, but it is 4-channel so you can add 2 more. I have a single camera set up at present and it just records non-stop - that gives me recordings back to 6 Aug.
Wired version
https://www.swann.com/uk/swdvk-445802v#! or on Amazon