I agree with the poster above re: IP cams, but I'd spend more and buy a POE Network Video Recorder to hook the cameras up to. You can still do all the motion alert stuff with the better NVR's but you have locally stored high quality video to review/give as evidence if anything happens. What's your budget?
Dahua and Hikvision are popular value for money brands. With many camera and NVR quality options. It all depends on the budget.
I've got this one Swann DVR8-4750 8 Channel 2TB CCTV Kit with 4 Cameras | Swann Home CCTV - https://www.safe.co.uk/products/swann-dvr8-4750-8-channel-4-camera-3-megapixel-cctv-kit.html its very easy to install and the picture quality is good although the frame rate is low but bearable.