You could do the ball raise/lower using a servo to push the ball up a tube when the weight of the ball on the tee shorts pin 4 to ground, and when the ball is removed pin 4 is unshorted and the servo moves the tee back down into the tube. code below.
//zoomkat servo button test 7-30-2011
int button1 = 4; //button pin, connect to ground to move servo
int press1 = 0;
digitalWrite(4, HIGH); //enable pullups to make pin high
press1 = digitalRead(button1);
if (press1 == LOW)