Drag GameObject with a Key

I'm used to use a mouse drag, code:

     // Use this for initialization
     void Start () 
     {
         path = Application.loadedLevelName + ".xls";
     }
     
     // Update is called once per frame
     void Update () {
         Screen.lockCursor = false;
         Cursor.visible = true;
         
         if (Input.GetKeyDown (KeyCode.R))
         {
             Application.LoadLevel("cozinha");
         }    
     }
  
     void OnMouseDown()
     {
         screenPoint = Camera.main.WorldToScreenPoint(gameObject.transform.position);
  
         offset = gameObject.transform.position - Camera.main.ScreenToWorldPoint(new Vector3(Input.mousePosition.x, Input.mousePosition.y, screenPoint.z));
  
          StreamWriter sw = new StreamWriter (path, true);
 
         sw.WriteLine (this.name + "\t" + Mathf.Round(Time.timeSinceLevelLoad));
 
         sw.Close ();
     }
  
     void OnMouseDrag()
     {
         Vector3 curScreenPoint = new Vector3(Input.mousePosition.x, Input.mousePosition.y, screenPoint.z); 
         Vector3 curPosition = Camera.main.ScreenToWorldPoint(curScreenPoint);
          transform.position = curPosition;        
     }    

But this only work when I press fire1 of mouse.

My question is: how can I do the same movement but this time using a keyboard key ?

This code works perfectly, but when I use cardBoard I don't have a mouse with me, I only have a Gamepand where gives me a 'K' of keyboard.

Thank you all.