For filling a hash, assignment to a hash slice is probably the best way:

my %index;
@index{@list1} = @list2;
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If you actually want a list as the result, rather than a hash, a for loop would work:

for (my $i = 0; $i <= $#list1; $i++) {
  push @result, $list1[$i], $list2[$i];
}
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The push could also be done as a nested loop, if there are lots of arrays to interleave.

Anyway, that's a very basic solution; much fancier solutions could be written to satisfy more requirements for the interleaving.