One method of hacking they do commonly used these days is "phishing" .
Now phishing is a kind of hacking whereby the replicate already.ade apps that are popularly used, and sometimes unpopular apps are also used too.
So when users try use this phished app the hacker gets hold of all the necessary information the need when the user inputs those information.
I've only falled for this kind of method once, when a friend of mine enlightened me on the situation.