The oil light is on and the engine sounds like a knocking noise, oil level is fine so what is the problem?
Your oil pump might not be working or you have an internal engine problem. Do not drive it anymore before you get it look at by a mechanic.
sounds like a oil pump to me as well the knocking noise is most likely the engine to dry to run so it starts to seize up from lack of lube
And have it towed to the mechanic of your choice. This is not a repair which can be performed on jack stands in the driveway, or shouldn't be.
Looking for a Used F-150 in your area?
CarGurus has 215,477 nationwide F-150 listings starting at $1,300.
Search Ford F-150 Questions
Ford F-150 Experts