Capan played an eight-hole stretch in 9 under, making an eagle on the par-5 ninth and following with seven straight birdies.
He two-putted for par on the par-4 17th, then hit into a fairway bunker on the par-5 18th and ended up saving par with a 7-foot putt.
"Whenever you're out there playing well and going low, I really just wanted to keep going as much as I could," Capan said.
"I know this course might be gettable the next few days, so just tried to get as many as I could."
Cristobal Del Solar shot the lowest round in Korn Ferry Tour history with a 13-under 57 in February in the Astara Golf Championship in Colombia. There have been 13 sub-60 rounds on the Korn Ferry Tour, six in the last 370 days.
The 58 broke the course record of 59 set by Masters champion Scottie Scheffler in a casual round with friends on May 3, 2020.
"When someone said it was for 58, I was excited because I know Scottie Scheffler shot 59, so whenever you can beat that guy, especially nowadays, I mean, you've got to take advantage," Capan said.
The 24-year-old Capan, making his 31st Korn Ferry Tour start, played at the University of Alabama and Florida Gulf Coast He previously shot 59 in the final round of a high school state championship
"I shot 59 before, so I thought, you know, may as well break that," Capan said. "It was a lot of fun out there. After the first four, five holes, I just felt really comfortable with my game and where I was at."
Trent Phillips was second after a 61. Tim Widing, the winner of the LECOM Suncoast Classic last week, had a 62.
The wind gusted to 30 mph on the mostly cloudy day, with a high temperature of 78.
