Speakers & microphones operate on the exact same principle. One is merely the inverse of the other.
Each uses a permanent magnet, a wire coil & a diaphragm.
If you send an AC current through a wire coil it generates a magnetic field. In proximity to a permanent magnet, this will cause cycles of attraction & repulsion. This is what makes your ...
Unfortunately setting the dB input isn’t as simple as that but don’t get too concerned with that part just yet. The Scarlett will be able to increase the level just fine. What is probably more important in your case is how far the microphone is from your mouth and how loudly you speak.