Hidden Cameras are notorious for most of the clips released on the Internet without the knowledge of the people who have been filmed in them. These hidden cameras come in a variety of shapes and sizes and are disguised so intelligently that is difficult to trace them.
Hidden cameras can come in the form of an alarm clock, in identification badges, an air purifier, an LCD monitor, smoke alarms, wall clocks, tissue boxes, rocks, books --- you name it – the product is available in almost every form you can possibly imagine. You even have spy or hidden cameras embedded into jackets.
Hidden cameras can be used for surveillance purposes. Similarly, worried parents can use hidden cameras, also called nanny cameras or wireless baby monitors, to ensure that their children are safe.
If you are worried about being a target by hidden cameras, you can use a hidden camera detector which uses a wireless signal detection technique to detect hidden cameras. You can even build your own hidden camera detector. For understanding how to do this, you could read this link at Wkihow, How to build your own hidden camera detector
To have a look at some hidden cameras for purchasing,you can refer to this website