If you have one array for keys and another for values, you can use the array_combine() function. 

<?php
$keys = array('first', 'second', 'third');
$values = array('apple', 'banana', 'cherry');

$combined_array = array_combine($keys, $values);

/*
$combined_array will be:
Array
(
    [first] => apple
    [second] => banana
    [third] => cherry
)
*/
var_dump($combined_array);
?>