The incident happened in the early hours of Sunday, May 1 in Ahoghill.
Detectives investiging the armed robbery are appealing for anyone who may have any information, including dashcam footage, to come forward.
Detective Sergeant Crothers said: “It was reported that at around 2.30am that a man, aged in his twenties, and woman, aged in her late teens, pulled up in a vehicle outside retail premises in the Galgorm Road area.
“An unknown man, armed with a knife, opened the passenger side door and shouted at the two victims to give him money.
“When the driver attempted to drive away, the suspect hung on to the car, before climbing inside, on top of the female passenger.
“There was an altercation inside the vehicle and the male injured party sustained a knife wound to his hand which required hospital treatment.
“The suspect then fled the scene on foot with a small sum of cash.
“He was described as being around six feet tall and was wearing a black tracksuit top with a full zip and hood, black tracksuit bottoms, black trainers and a black baseball cap with a logo on it. He was also wearing a black and camouflage face mask.
“This was a terrifying ordeal for both of the victims and our enquiries are ongoing.
“We would ask anyone who may have any information, including dashcam or other footage to contact police on 101 quoting reference 1145 2/5/22.”
Alternatively, you can submit a report online using the non-emergency reporting form via http://www.psni.police.uk/makeareport/
You can also contact Crimestoppers anonymously on 0800 555 111 or online at http://crimestoppers-uk.org/