Jump in a 3d game using charachter controller

Hey everyone, ive been working on a simple 3d game where i use a charachter controller to move the player. I've been trying to implement jump into the game for a while now, and it's to late to try a different movement system. What's the best way i can implement it?

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class PlayerController2 : MonoBehaviour
 {
     [SerializeField] Transform playerCamera = null;
     [SerializeField] float mouseSensitivity = 3.5f;
     [SerializeField] float baseSpeed = 6.0f;
     [SerializeField] float sprintSpeed = 12.0f;
     [SerializeField] float currentSpeed;
     [SerializeField] float gravity = -20.0f;
     [SerializeField] [Range(0.0f, 0.5f)] float moveSmoothTime = 0.08f;
     [SerializeField][Range(0.0f, 0.5f)] float mouseSmoothTime = 0.08f;
     private Vector3 playerVelocity;
     float cameraPitch = 0.0f;
     float velocityY = 0.0f;
     CharacterController controller = null;
 
     Vector2 currentDir = Vector2.zero;
     Vector2 currentDirVelocity = Vector2.zero;
 
     Vector2 currentMouseDelta = Vector2.zero;
     Vector2 currentMouseDeltaVelocity = Vector2.zero;
 
     void Start()
     {
         controller = GetComponent<CharacterController>();
         Cursor.lockState = CursorLockMode.Locked;
     }
 
     void Update()
     {
         if (Input.GetKey(KeyCode.LeftShift))
         {
             currentSpeed = baseSpeed + sprintSpeed;
         }
         else
         {
             currentSpeed = baseSpeed;
         }
 
         UpdateMouseLook();
         UpdateMovement();
     }
 
     void UpdateMouseLook()
     {
         Vector2 targetMouseDelta = new Vector2(Input.GetAxis("Mouse X"), Input.GetAxis("Mouse Y"));
 
         currentMouseDelta = Vector2.SmoothDamp(currentMouseDelta, targetMouseDelta, ref currentMouseDeltaVelocity, mouseSmoothTime);
 
         cameraPitch -= currentMouseDelta.y * mouseSensitivity;
 
         cameraPitch = Mathf.Clamp(cameraPitch, -90.0f, 90.0f);
 
         playerCamera.localEulerAngles = Vector3.right * cameraPitch;
 
         transform.Rotate(Vector3.up * currentMouseDelta.x * mouseSensitivity);
     }
     void UpdateMovement()
     {
         Vector2 targetDir = new Vector2(Input.GetAxisRaw("Horizontal"), Input.GetAxisRaw("Vertical"));
         targetDir.Normalize();
 
         currentDir = Vector2.SmoothDamp(currentDir, targetDir, ref currentDirVelocity, moveSmoothTime);
 
         if (controller.isGrounded)
             velocityY = 0.0f;
 
         velocityY += gravity * Time.deltaTime;
 
         Vector3 velocity = (transform.forward * currentDir.y + transform.right * currentDir.x) * currentSpeed + Vector3.up * velocityY;
 
         controller.Move(velocity * Time.deltaTime);
     }
 }