Move Image Banner to Functions.php

//Load Banner For All Pages
function pageBanner(){ 
?>
    <!--Banner Start-->
    <div class="page-banner">
        <!-- <div class="page-banner__bg-image" style="background-image: url(<?php //$pageBannerImage = get_field('page_banner_background_image'); echo $pageBannerImage['url']; ?>)"></div> -->
        <div class="page-banner__bg-image" style="background-image: url(<?php $pageBannerImage = get_field('page_banner_background_image'); echo $pageBannerImage['sizes']['pageBanner']; ?>)"></div>
        <div class="page-banner__content container container--narrow">

        <?php //print_r($pageBannerImage) ?>

            <h1 class="page-banner__title"><?php the_title(); ?></h1>
            <div class="page-banner__intro">
            <p><?php the_field('page_banner_subtitle'); ?></p>
            </div>
        </div>
    </div>
    <!--Banner End-->
<?php }

Load pageBanner();

    while(have_posts()){
        the_post(); 
        //Page Banner From Function.php
        pageBanner();
        ?>