Detecting Cameras

Hi guys

I have a question about cameras. Suppose there are

(1) hidden ip cameras

(2) dvr cameras

How would you go about detecting them without using anfryip scanner or kismet?

Suppose you are at the mall, and that there are cams, suppose you want to tap into them. One person talked about hacking the dvr...etc...it would be great if you could let me know how to tap into the feed.