ACF Pro Widget Custom Fields - WordPress action

actions.php

<?php
// Replace the values below with the field names configured in ACF.

function cs_dynamic_sidebar_params( $params ) {

  // bail early if ACF is not active
  if (!function_exists('get_field')) return $params;

  // get widget vars
  $widget_name = $params[0]['widget_name'];
  $widget_id = $params[0]['widget_id'];

  // bail early if this widget is not an HTML widget
  if( $widget_name != 'Custom HTML' ) return $params;

  // add image to before_widget
  $image  = get_field('widget_image', 'widget_' . $widget_id);
  $button = get_field('widget_button', 'widget_' . $widget_id);

  if( $button )
    $params[0]['after_widget'] = '<a class="btn btn-lg d-block btn-secondary" href="' . $button['page'] . '">' . $button['text'] . '</a>' . $params[0]['after_widget'];

  if( $image )
    $params[0]['after_widget'] = '<img alt="" src="' . $image['url'] . '">' . $params[0]['after_widget'];

  // return
  return $params;
}
add_filter('dynamic_sidebar_params', 'cs_dynamic_sidebar_params');