I am installing kitchen cabinets (bottom) on a wall with a electrical outlet near baseboard. I need to raise it above countertop. Is this difficult?

Not difficult at all since your route will be covered by the new base. Establish the locatoion for the new box, hoopefully directly above the old receptacle. Open the existing box after killing power to the circuit. Make a small hole in the wall directly above the existing box so you can see how to remove a slug from the box, run a steel snake or sewer rodder down the wall from new to old, pull a short piece of 14-2 cable (12-2 if 20 amp)up from old to new. Connect new wires to old with wire nuts and seal the old receptacle with a solid plate. Need more?