So, you want to know how to snoop on people, eh? Technically, you shouldn't be doing that as such activities might get you in serious trouble, not to mention that invading other people's privacy is wrong on so many levels. In case you are willing to take the risk, you can probably find a company online that specializes in developing spy software for smartphones. However, the apps and services they offer usually don't come cheap, even though they could prove pretty effective.
Alternatively, there are Android spy apps that can work in a similar fashion, allowing one to eavesdrop on conversations or to capture photos and video without other people knowing. Moreover, many of them don't cost anything, so anyone with an Android smartphone is free to give them a shot. We have to warn you, however, that the software we have selected was made just for fun. That said, don't use the apps for anything illegal or morally wrong, and don't blame it on us in case you get caught. You've been warned!