Hidden spy cameras are very effective tools when it comes to finding out what is going on when you are not there. They have so many uses at home or business. See what the kids are doing when you are not around, find out how your nanny takes care of your kids, see if you have a cheating spouse, see what your employees are stealing from you, etc.
A hidden camera is simply a board camera hidden inside an object that is a simple everyday object that no one suspects is actually a covert surveillance tool. Now the way most of them work is to hook up wires for wired models to a DVR or VCR to record the images then playback over a monitor.
