The end of the connector is put on the brain or heart of somebody, and the other end is stuck to the head of the other person. But when Plankton puts this cable on SpongeBob's heart and the other end on his head, he then morphs into SpongeBob. The same transformation goes for Patrick.
The Mind Connector was built out of two pink pieces resembling a sink plunger's rubber cap, which were stuck to a reddish-brown cable. If one button is pressed, the pink cap attached to the operator's head completely wraps around him, making him look like a hot dog wiener.