manifest.json

{
  "dependencies": {
    "jp.keijiro.midi-jack": "https://github.com/keijiro/MidiJack.git#upm",
    ...
  }
}

MidiInputController.cs

using MidiJack;
using UnityEngine;

public class MidiInputController : MonoBehaviour
{

    private void HandleMidiKnob(MidiChannel channel, int knobnumber, float knobvalue)
    {

        Debug.Log($"{channel}, {knobnumber}, {knobvalue}");

    }

    private void OnEnable()
    {

        MidiMaster.knobDelegate += HandleMidiKnob;

    }

    private void OnDisable()
    {

        MidiMaster.knobDelegate -= HandleMidiKnob;

    }

}