Many times cable develops tears in the insulation that makes it “leak” signal and this signal can be captured by a nearby directional Over The Air antenna. The cable companies work hard to detect signal leaks, you may have noticed cable company vans with a bunch of antennas from time to time, these detect leaks and signal thieves. if someone in your area is getting cable illegaly and is using cheap RG-59 cable, that cable will leak signal that can also be captured. If succesful, only a few analog channels will be visible and the quality will be very bad, by law you are required to report any signal leaks to the CATV company.
To legaly get more channels, get yourself an HDTV and a good antenna in your roof so you can get free over the air channels in addition to your current analog. Dont bother with indoor antennas as these are hardly sensitive, even the really expensive ones, nothing beats a roof top antenna, made even better with a rotator motor. OTA HDTV signals can travel a long distance with minimal loss so if you invest in a good antenna and a rotator , $100 or more , you may get channels from far away places, The hobby is called TVDXing