How do I make my character move on the Z axis on 2d rigidbody?

Im using rigidbody2ds velocity feature for movement and i need to move my character on the Z axis, problem is I cant figure out how to enable the Z axis for rigidbody 2d. It's a topdown roguelike sprite game with movement similar to binding of isaac. This is my current script.

 using UnityEngine;
 
 /// <summary>
 /// Player controller and behavior
 /// </summary>
 public class PlayerScript : MonoBehaviour
 {
     /// <summary>
     /// 1 - The speed of the ship
     /// </summary>
     public Vector3 speed = new Vector3(50, 50, 50);
 
     // 2 - Store the movement and the component
     private Vector3 movement;
     private Rigidbody2D rigidbodyComponent;
 
     void Update()
     {
         // 3 - Retrieve axis information
         float inputX = Input.GetAxis("Horizontal");
         float inputZ = Input.GetAxis("Vertical");
         float inputY = Input.GetAxis("Y");
 
         // 4 - Movement per direction
         movement = new Vector3(
           speed.x * inputX,
           speed.y * inputY,
           speed.z * inputZ);
 
         // ...
 
         // 5 - Shooting
         bool shoot = Input.GetButtonDown("ArrowRight");
         bool shootup = Input.GetButtonDown("ArrowUp");
         bool shootdown = Input.GetButtonDown("ArrowDown");
         bool shootleft = Input.GetButtonDown("ArrowLeft");
         // Careful: For Mac users, ctrl + arrow is a bad idea
 
         if (shootdown)
         {
             WeaponScriptDown weaponup = GetComponent<WeaponScriptDown>();
             if (weaponup != null)
             {
                 // false because the player is not an enemy
                 weaponup.Attack(false);
             }
         }
         if (shootleft)
         {
             WeaponScriptLeft weaponup = GetComponent<WeaponScriptLeft>();
             if (weaponup != null)
             {
                 // false because the player is not an enemy
                 weaponup.Attack(false);
             }
         }
         if (shootup)
         {
             WeaponScriptUp weaponup = GetComponent<WeaponScriptUp>();
             if (weaponup != null)
             {
                 // false because the player is not an enemy
                 weaponup.Attack(false);
             }
         }
         if (shoot)
         {
             WeaponScript weapon = GetComponent<WeaponScript>();
             if (weapon != null)
             {
                 // false because the player is not an enemy
                 weapon.Attack(false);
             }
         }
 
         // ...
 
     }
 
 
     void FixedUpdate()
     {
         // 5 - Get the component and store the reference
         if (rigidbodyComponent == null) rigidbodyComponent = GetComponent<Rigidbody2D>();
 
         // 6 - Move the game object
         rigidbodyComponent.velocity = movement;
 
         // 7 - Z axis in rigidbody
         
     }
 }