Something similar to what this guy is wearing on his tie:
The "guy" is wearing a lapel mic. Also known as a lavalier mic. A quick excerpt from the Wikipedia page:
A lavalier microphone or lavalier (or lav or lapel mic) is a small electret or dynamic microphone used for television, theatre, and public speaking applications, in order to allow hands-free operation.
With search terms in hand, you'll find many resellers. Good luck :)