Chapel Hill police said the robbery happened at a Sun Trust branch inside a Harris Teeter grocery store on Martin Luther King Jr. Blvd.
The suspect entered the bank around 3:45 p.m. wearing a surgical mask and a construction vest and handed a bank teller a note.
The suspect is described as a 5-foot-tall white male with a very pale complexion. Officials said he indicated he had a weapon, but never showed one. The suspect left the scene in a black or dark blue Dodge Avenger.
Anyone with information is asked to call Chapel Hill police.