Do players use poker program to help improve their game? Would it be possible for the opponent to see your cards?
Some players do use programs to improve their games. I've never used one so I don't know how they work, but they do exist.
With seeing your cards, it is possible, but very unlikely. It would require a malicious third party program which tracks your hand and sends the data across to another person, which is not very useful unless said person is on the same table as you. So yes, possible, but very very very unlikely