Exterior Home security/Lighting compatibility
Several companies make separate Passive Infrared (PIR) detectors that could be used for your purpose. Or you could just mount motion detector lights in chosen locations or on the outside of the house. That is what most people opt for. Tying the whole thing together could be done but at an added cost that most people don't want to spend for what they get out of it.

Half of solving all design problems is getting familiar with the available products. This comes from experience and research. Spend some time browsing the net for motion detector type lights and sensors. You will find lots to choose from.

Good luck!