Here is another RPi based video surveillance solution to follow which uses MotionPie which in turn is based on Motion a Linux Back-end which can detect motion within video or still picture formats.

This seems a quick and straightforward implementation with RPi OS and download and install of MotionPie.

Now to find a RPi case with camera mount. UzERP’s site show’s Nwazet case I think.

Via Setting up Raspberry Pis as CCTV Cameras with MotionPie.