The term "hack" is grossly misused by the media and the general public. "Hacking" is elevating a practical technical skill to an elegant, unusual, or bizarre art-form. Some people hack code. Some people hack computer hardware. My dad hacks farm equipment.
The term "crack" is probably what you are looking for: The malicious or illegal use of technical skills for lulz, personal gain, or just to be an annoying pain in the behind. Here's a guide for how to become a cracker:
First, get a leather jacket and leather pants. Yes, leather pants really -do- have spikes on the inside.
Second, you need to get an acoustic modem. That's right, one of the ol' 56k gurgly doohickies that hooks up to your phone line and acts like a serial port. Bonus points here if you also install a qwk reader.
Third, you need to find a dialup BBS that is still in operation. When you find one, connect to it and look for the "filez" section. Beneath that, look for the "phreak/hack" subsection. Download every file, then read them all. If you need to meet an upload quota first, make a bunch of ANSIs and upload them.
Fourth, you need to build a bluebox. Don't let anyone tell you that it won't work on a modern phone system, just keep trying until you get it working.
Fifth, you need to build a flux capacitor and go back in time to 1983, when 2600 Hz really would give you a trunk line and people still used sendmail.