Get a float from a different GameObject? (MouseLook)

I need to access a public float from the fps controller’s mouselook script. I think it is on the player? It is accessed from FirstPersonController script like it is in a drop down in the inspector. It is [Serializable].
Why doesnt this work? (im a noob and need help making a sensitivity slider and I cannot find it anywhere, if anyone has a script for that (FPSController) I would love to have it. How do i access the float? (My scirpt):

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityStandardAssets.Characters.FirstPerson;

public class sensitivitySliderScript : MonoBehaviour {
    public MouseLook m_MouseLook;
    public float xfloat;

    private void Start()
        xfloat = MouseLook.XSensitivity;

    void Update () {


       // PlayerPrefs.SetFloat("currentX", MouseLook.XSensitivity);

     //   MouseLook.XSensitivity = PlayerPrefs.GetFloat("currentX", 0);


MouseLook floats I need:
using System;
using UnityEngine;
using UnityEngine.UI;
using UnityStandardAssets.CrossPlatformInput;

namespace UnityStandardAssets.Characters.FirstPerson
    public class MouseLook
        public float XSensitivity = 2;
        public float YSensitivity = 2;

There are 2 solutions for you :

either you have to replace your line xfloat = MouseLook.XSensitivity; by xfloat = m_MouseLook.XSensitivity;


your XSensitivity variable has to be static, like this : public static float XSensitivity = 2;
then your line xfloat = MouseLook.XSensitivity; will be ok and the line public MouseLook m_MouseLook; will be useless because XSensitivity will be accessible from all scripts.