how to change array structure in laravel?

Hello everyone i get some problem when try learn php with laravel, there is the problem ...

i have an array structure like this :

array:3 [▼
  0 => 16
  1 => 19
  2 => 15
]

how can u change the array structure to look like this :

array:3 [▼
  0 => array:1 [▼
    0 => 16
  ]
  1 => array:1 [▼
    0 => 19
  ]
  2 => array:1 [▼
    0 => 15
  ]
]

im newb ,can somebody help me, im using laravel 5.8 ,very grateful if someone helps. sorry for my broken english.

via Chebli Mohamed