When installing an IPV15 with its accompanying remote sensor, the IPV0R, the sensor needs to be installed in a box with a load connection. The IPV0R must be in a box with a hot +netural wire.
The sensor also needs a hot and neutral connection, so if there's only one wire in the box, I'm not sure how you can make this application work. I'm also unsure as to why there'd only be a single wire in the box. I strongly recommend contacting a licensed electrician to have them inspect the wiring of the home, since without properly identified wires, it is unsafe to provide wiring instructions.