Sebha has an international airport (SEB) with some connections to Tripoli and Benghazi, though services are limited and subject to change given Libya's political situation. The overland journey from Tripoli is about 750 kilometres through the desert — a long day's drive on a good day, requiring preparation and usually done in convoy. Check current road security conditions carefully before attempting overland travel in Libya.
The situation on the ground in Libya changes, and any visit should be preceded by thorough research into current conditions. Travel to Sebha and the Fezzan has historically been possible for organised expeditions with local guides and appropriate permits, but independent travel carries significant risks.