As others advice, frigate is great. You can set this up under home assistant, which is a smart home open source OS/software and even if you have no plan of doing smart home, it is very handy as you can easily create automation which can send you notification with pics, will trigger an alarm, turn on lights... If you don't already have device powerful enough to run frigate, I would advise to look for a mini pc with n100 or n150 processors, they are not very expensive (around 150€) and don't consume much electricity (close to raspberry pi 5 while being more powerful).