When you attach / detach S Pen on Samsung Galaxy Note series, a tone goes off. To enable and change the played sound, or disable S Pen sound on Galaxy Note, Note 2, Note 8 do as follows:
1. Open "Settings" App
2. Go to "S Pen" settings
3. Tap "Pen attach/detach sound"
4. To disable S Pen sound, choose Off, otherwise choose one of the existing sounds.