Cauley's 63 was one over his personal best and two more than the tournament record of 61 set by David Frost in 1994.
"You never go out thinking 'you're going to shoot that,'" Cauley said. "I just got into the round and was swinging well and tried to give myself as many looks as I could."
Cauley recorded four birdies on the front nine and four more on the back without a bogey en route to an opening round eight-under par on Thursday.
He is two strokes ahead of England's Luke Donald, Canada's Graham DeLaet and American Sam Saunders. A half dozen others sit three shots off the pace.
Cauley's 63 was one over his personal best and two more than the tournament record of 61 set by David Frost in 1994 and matched by Troy Merritt in 2015.
Cauley failed to make the cut in two of his previous three appearances at the RBC Heritage and has never finished better than third on the PGA Tour.
Many of the world's best golfers decided to skip this event after taking part in the Masters. Just five of the world's top 25 are competing, with No. 16 Tyrrell Hatton topping the list.
Reigning champion Branden Grace is tied for 19th with a three-under 68.
American Jim Furyk, world No. 17 Matt Kuchar and German Martin Kaymer join South Africa's Grace in a large group at three-under. Grace held the first round lead en route to his 2016 victory.
Japan's Hideto Tanihara is one of eight players at four-under while England's Ian Poulter and Kiwi Danny Lee highlight the group at five-under.