Foo.cs

using UnityEngine;

public class Foo
{
    private readonly int _hoge;
 
    public Foo(GameObject target, int hoge)
    {
        _hoge = hoge;
        target.AddComponent<FooBehaviour>().Init(this);
    }
    
    private class FooBehaviour : MonoBehaviour
    {
        private Foo _self;
        
        public void Init(Foo self)
        {
            _self = self;
        }
        
        private void Update()
        {
            Debug.Log(_self._hoge);
        }
    }
}