You can use Tie::Handle to capture the output to a scalar and then do what ever you need to it.

package NewHandle;
require Tie::Handle;

@ISA = qw(Tie::Handle);

sub WRITE { $self = shift; $main::text .= shift; }
sub TIEHANDLE { bless { }, shift; }
package main;

use strict;
use warnings;

our $text;
print "before: $text\n";

{
  local *STDOUT;
  tie *STDOUT, 'NewHandle';

  mysub();
}
print "after: $text\n";

sub mysub {
  print "mysub", " output\n";
}

1;
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