Solid Hardwood, Engineered and Laminate Flooring - Laminate flooring over hardwood floors

Can a laminated floor be installed over an existing hardwood floor? The hardwood floor is about 40 years old and creaks and squeaks which is very annoying! Can anything be done to the hardwood floor so it doesn't squeak so we don't have to put a laminate floor? or does the hardwood floor have to be taken out for the new laminated floor to go in? TIA

You can install laminate on top of a hardwood floor.
However, it's very likely that you will still have sqeaking.

If you can get at the underside of the floor from a basement or something, then you could attempt to remedy the squeaks.

If squeak is in subfloor, then this will require, as indicated, accessing beneath to shim any gaps between subfloor and joists. This requires someone beneath the floor and someone walking on floor above to identify squeaks for the person below to attempt to shim. If squeaks are a result of flooring boards rubbing against nails or each other, drilling pilot holes and face-nailing with finishing nails the affected boards to secure them will likely correct the squeaks. Nails will need to be countersunk with nail punch and holes filled. Adding additional flooring over squeaky wood floors will not resolve the squeaking problems.