How about a mini tape recorder that has a pinhead microphone disguised as a tie tack?
From the time.com
Maybe he wore flag cuff links or a flag tie tack.
From the washingtonpost.com
That was her father's tie tack.
From the nytimes.com
Plus, I like uniforms and I would get to wear one, along with a white shirt and a tie, even a tie-tack in the shape of airplane wings.
From the npr.org
The positive part of this story is that seeing all his sons and grandsons achieve their Eagle was a goal of Irving and at the ceremony, Scott was able to honor him and give him an Eagle tie tack.
From the ocregister.com
Currently the wiring and batteries fit in a ladies'clutch, but he hopes to continue reducing the size of the device to the point that it could be worn in something as small as a pendant or tie tack.
From the techcrunch.com
The Phils stormed back to tie the score the in the bottom of the inning and tack on five more in the fifth.