when you leave your house you want to see what your pet is doing, right? My first thought is to buy a home safety camera like a nest camera of a pet cube,but those can be extremely expensive so I will build it with a raspberry pi.
list of needs:
rasberry pi (preferibly the 3rd one)
camera interface for rasberry Pi
case with wall mounts
screws
small monitor
keyboard and mouse
first put the rasberry pi in its case and connect the camera. Next place the screws in a place where it can monitor your pet,mount the screw holes and then the pi.
setup a online video streaming account by connecting the keyboard and mouse and then the monitor, then unplug it and you are ready to monitor!