Andrew Magee is the only golfer to accomplish what singular feat (and we need you to be specific here) during a match on the PGA tour, accomplishing this on the 17th hole during his first round at the 2001 Phoenix open (with the assistance of Tom Byrum's putter, off which his ball bounced on its way to history). We'll be liberal on the wording, but be specific! (Hint: Aaron Baddeley sort-of did this on the 17th hole of the opening round of the Texas Open in 2015,, but a one-stroke penalty negated this on the scorecard).
Hole in One on a par-4 hole (edited at 11:48 pm, October 24, 2017 (CEST))
Original Answer: Hole on One on a par-4 hole