Final answer:
The technique commonly used in both the overhand serve and spike in volleyball is hitting.
Step-by-step explanation:
The technique commonly used in both the overhand serve and spike in volleyball is Hitting. In both movements, the player uses a hitting motion to strike the ball with force and accuracy. When serving, the player throws the ball up in the air and hits it over the net into the opponent's court, while during a spike, the player jumps and hits the ball downward towards the opponent's court.