How would I apply a camera image effect with increasing intensity as the enemy gets closer to the player?

Hi all,

I am trying to add the chromatic aberration camera effect when the player gets close the enemy. I have this script, but I was wondering how I could make the effect increase as the player gets closer to the enemy.

  using UnityEngine;
  using System.Collections;
  using UnitySampleAssets.ImageEffects;
  
  public class ChangeCamEffects : MonoBehaviour {
  
      public GameObject MainCam;
  
      public void DoStuff() {
  
          MainCam.GetComponent<VignetteAndChromaticAberration> ().chromaticabberation= 5;
  
      }
  
  }