The following project will show how you can use a laser pointer to hear noises from hundreds of feet away (the distance will be relative to the strength of the laser).
Clip the earphones off your old headphones, and strip back the protective conduit to expose three wires (red, white, and black).
There are two contacts on the photocell. Solder both the red and white wires to one contact, and the black wire to the other.
Plug the headphone jack into your laptop or other recording device.
Using binder clips or duct tape, secure the photocell to something sturdy so that it can be easily moved and aligned.
Again using your clips or tape, attach the laser to your tripod and secure the power button so the laser remains on.
Find a room with a window you'd like to spy on, and aim the laser at the window at an angle.
Determine where the laser reflects, and situate your photocell so the reflected beam hits the front of the cell.
Hit record and listen!