This is another of those bits of memorbilia that would have been about in the sixties - a pen that is really an A M radio.
This is the Get Smart version although I suspect there would have probably been variations promoting other sixties spy shows.
It's obviously a simple crystal set and needs no batteries. It uses a clip to attach to any metal object in the room to provide the arieal, but I'd imagine the reception would be a little hit and miss, although the novelty value is what it's about.
I remember an early episode of The Man from UNCLE using a radio transmitter disguised as a cigarette packet using the similar method of attaching the antenna wire to a metal object in the room. That was before UNCLE agents got pen radios!