Hey there @Foreignprince80! Speech recognition is actually quite a complex topic! If you were to build it from the ground up it would take lots of work. Though if I were to point at two free plugins that might be able to do what you need, here’s some possible recommendations.
Runtime Audio Importer is a plugin that let’s you import audio in engine during runtime. This would be perfect for capturing audio from microphone input:
Then passing that audio to Runtime Speech Recognizer, which as the name implies can give offline speech recognition.
I actually plan to use these both in conjuction myself on my own project soon, but as of now I have not tested each plugin, so if you end up going this route, let me know how it goes!