Did not get sever response header when mpm_event and php-fpm is enabled

Question

When I used mpm_prefork module in Apache server then Apache_response_headers work properly and give response header but when I enabled mpm_event and PHP-fpm then this function not work so is there any function which can give the server response header in mpm_event and PHP_fpm module.

if(function_exists('apache_response_headers'))
    {
    $responseHeaders  = apache_response_headers();
    getResHeaders($responseHeaders);
    }

This code is running when the mpm_prefork enabled but if i will enabled mpm_event and php-fpm then if condition will not execute so add a else condition and use such function which can give the server response header . Note-I want server header response not request header.