I assume you mean engine ECU (Engine Control Unit)
Its not a straightforward swap, as the engine ECU
has to match the immobiliser and key transponders. As far as I know you can't simply use the T4 (Testbook version 4.Computer Diagnostic System)
to do the swap, but I'd expect there are people around with the tools to sort it out.
The other thing to bear in mind is that depending on what engine variant you have, some of the newer ones have extra sensors. Example the diesels have a post intercooler air temperature sensor, later V6s have a post catalyst lambda probe as well as the two precept ones.
In summary, not just plug in and go.