I believe that Apple's portable lines use surface mount technology, which means that the parts are mounted directly to the circuit board using specialized machinery common in the electronics industry.
There are few, if any, MacBooks made in the last decade that use socketed CPUs or GPUs. In fact, recently, Apple has taken to removing the sockets for RAM and storage (SSDs) meaning that you are stuck with the configuration as bought.
I have absolutely no doubt that someone with experience working with surface mounted parts could get the CPU/GPU off the PCBs. But then how are you going to mount the removed parts to another board?
You might be able to extract the system board from the case and then set it up to do as you would like, but removing parts from the PCB? Doubt it.