How to insert array to array PHP

Solution 1:

You don't need "array_combine()", "array_slice()" or similar. Just iterate through the data and create a new one:

$a = [2.2, 1.1, 3.9];
$b = ["B", "C", "F"];

$new = [];
foreach ($a as $index => $value) {
    $new[] = [
        $b[$index], // Fetch the value with the same index from the other array
        $value
    ];
}

Demo: https://3v4l.org/oseSV

Solution 2:

You can use array_map to iterate over two arrays simultaneously and produce a new array:

$distance = array(3) {
  [0]=>
  float(2.2)
  [1]=>
  float(1.1)
  [2]=>
  float(3.9)
}
$getID = array(3) {
  [0]=>
  string(1) "B"
  [1]=>
  string(1) "C"
  [2]=>
  string(1) "F"
}

$output = array_map(function ($d, $id) {
    return [$id, $d];
}, $distance, $getID);

Note that this code assumes that both arrays have the same length.

Offtopic:

A little advice about your code: always name your variable with something that allows you to know what's inside it, using correct plural too:

Your $distance variable contains an array off distances, so it nsme should be in plural.

Your $getID is not a function, so it should not be called get, but just $Ids instead.