Hacker element is not used often in Little Alchemy 2, but it can be used to combine Computer, Idea, and Statue, and it is needed for any elements associated with computer and internet. The process of making Hacker is not easy but not too hard, you need to make Life, Human, Stone, Glass, and finally Hacker. Check out the detailed instructions and try it yourself.
Fire + Earth = Lava
Lava + Earth = Volcano
Water + Water = Puddle
Water + Puddle = Pond
Water + Pond = Lake
Lake + Lake = Sea
Earth + Sea = Primordial Soup
Volcano + Primordial Soup = Life
Earth + Water = Mud
Air + Air = Pressure
Earth + Pressure = Stone
Air + Stone = Sand
Sand + Mud = Clay
Clay + Life = Human
Sand + Fire = Glass
Glass + Glass = Glasses
Glasses + Human = Hacker