What is clicking noise I hear when turning headlights on and off on Subaru Forester?

There is probably a relay switch that is being energized when you turn on the headlamp switch. In order to keep the wires and switch small in the cabin controls, they put the heavy guage wire & switch elsewhere. You turn the switch and it energizes the relay which is electromachanically switched and it makes a small metallic click. Visit acmehowto.com for answers to common household repair questions.