The 21-year-old has moved to the Clarets after spending five years at United.
The Tunisia international joined our youth system from Monaco in 2019, and has since gone on to make 13 first-team appearances for the club.
Hannibal became the 239th graduate from our Academy in 2021, when he made his first-team debut against Wolves, just three days after being named as our Denzil Haroun Reserve Player of the Year.
He scored his only senior goal for the Reds in 2023, netting from long range in a 3-1 defeat to Brighton & Hove Albion at Old Trafford.