If you look at the employees' timecards (through either Dashboard or Timcards), you will see a little note icon whenever your employees leave a note with their punch.
If it's unread, it should be spinning, unless the setting was changed.
To check this, you can look at My settings and check Note Status Type and Note Status Indicator.
Note Status Type can be None / Shared / Individual, and determines the visibility of your notes.
Note Status Indicator can be Static / Spinning. If it's set to Static, all notes will appear the same. If it's set to Spinning, any notes which you have not opened will spin to indicate that they are unread.