When something snicks, it makes a small, sharp sound, like when you close a door quietly.
Snicks are usually quiet and quick sounds.
Examples:
The door snicks shut.
I heard the lock snick into place.
She snicks the light switch off.
The cat's tail snicks against the table.
The snick of the scissors was very loud in the quiet room.
The snick of the closing box was the last thing I heard.