use warnings;
use strict;

my @a1 = map{"k$_"} 1..3;
my @a2 = map{"m$_"} 1..3;
my @a3 = map{"d$_"} 1..3;

my $href;
for my $i (0 .. $#a1) {
    $href->{$a1[$i]} = {Metadata => $a2[$i], Submitted => $a3[$i]};
}

use Data::Dumper; $Data::Dumper::Sortkeys=1; print Dumper($href);

__END__

$VAR1 = {
          'k1' => {
                    'Metadata' => 'm1',
                    'Submitted' => 'd1'
                  },
          'k2' => {
                    'Metadata' => 'm2',
                    'Submitted' => 'd2'
                  },
          'k3' => {
                    'Metadata' => 'm3',
                    'Submitted' => 'd3'
                  }
        };