Replacing Motherboard With Newer Model

Okay so I have a late 08 MacBook. The shell says MacBook Pro at the bottom of the screen, but the About This Mac section just says MacBook. It makes mew think that I'm running a Macbook motherboard in a Pro Shell. (if that's even possible, idk I have very limited knowledge on this stuff)

My Question is, can I replace the motherboard in this shell to technically run a newer model of MacBook so that I can get the High Sierra Software, instead of being limited to El Capitan? It'd be much easier and cost efficient to do this instead of buying a whole new computer, so thanks!