0.5 "force sensitive resistor (FSR) is a quick way to measure the pressure, and is very easy to setup. FSR depending on how much pressure is applied to the sensing area, its resistance to change. The greater the ball, the less resistance. When measured with a multimeter , the sensor is greater than 1MΩ when no pressure is applied to a resistance.
As an example, we have a simple resistor voltage divider circuit using an Arduino UNO and will measure the force.