Pin Annotation in unity3d on a 3D model

Hi Is it possible to have a pin annotation on a 3D model , like we have pin annotation in Maps , where we can drop pins on a map for annotation , similarly can we drop pins on a 3D model in unity.

I thought it could be possible if i would have a add pin button in my screen which upon pressing would create a 3D game object(PIN) which user can drag and drop on top of another 3D model .

Please guide me in right direction .

Regards