Answer: Their body.
A research team at the Embedded Systems Laboratory developed the FlyJacket, a soft exoskeleton, with beginner unmanned aerial vehicle (UAV) pilots in mind. The device is worn on the upper body along with a virtual reality headset. The idea is for the pilot to feel as though they are the one in the air and uses intuitive upper body gestures to fly the drone.
To use the suit, pilots sit with their arms extended like wings (there are supports to prevent their arms from getting tired). A smart glove on one hand allows them to tell the drone when to take off and land by pressing the tips of their pointer finger and thumb together. The same gesture using the middle or ring fingers during flight will flag points of interest.
To move the drone itself, the pilot simply tilts and/or turns in the direction they want to go. Motion sensors embedded in the suit detect these movements and the drone responds. For example, bending backward will tell the drone to go up.
Check out the FlyJacket in use in the video below.