Using just power from ethernet cable for security camera?
I don't believe you need to spend the big bucks for POE, as your requirements are straightforward. If you would install CATx cable for POE, you can easily enough install a pair of wires and add a micro usb pigtail at the camera end. Even though you are running only 5V, to reduce voltage drop, consider to run something as large as 16 gauge wire to the pigtail. Ensure that you provide correct polarity on the added wiring, of course.