I'm sorry but you can't since if u use up a customized cpu than the original itself, you'll blow the phone up or fried the motherboard.
You can tho but you've got to change all of the coding in the system or wiring. It's better to stay stock. Converting NVIDIA GTX 1060ti into a eGPU for my laptop costed me the laptop body itself since i've got to remove some ports and wiring in the body, so if i don't want to use the eGPU i've got to reverse engineer it again :/