Wireless Security Alarm

okay i am just starting out as a private investigator and i need to to what kind of hidden camera/ reciever system i should buy it has to be completely wireless and motion sensing would be prefered it needs to have multiple camera hook ups and have a long range
can anyone help?

Where could someone purchase a miniature wireless security camera that works decently? At least good enough to tell who’s doing what. I have some strange, unexplainable things happening inside and outside my home and am trying to determine what is going on. I have located things for outside the home, but haven’t came up with a affordable miniature wireless security camera or even a hidden camera of some sort for inside the home. Any Ideas?