This works even for flexible content fields. Just inspect the field in console when in admin and snab the data-key name from there.

enqueue_if_acf_field_is_used.php

<?php
add_action( 'wp_enqueue_scripts', 'sp_register_acf_field_scripts', 5 );
function sp_register_acf_field_scripts() {
  // Plugin file
  wp_register_script( 'siema-js', get_stylesheet_directory_uri() . '/bower_components/siema/dist/siema.min.js', array(), '', true );
  
  // Custom functionality
  wp_register_script( 'siema-init-js', get_stylesheet_directory_uri() . '/library/js/siema-init.js', array(), '', true );
}

/* Inspect ACF field in admin to get correct key name */
add_filter('acf/load_field/key=field_5922a0d922cce', 'sp_load_field_assets');
function sp_load_field_assets( $field ) {
  wp_enqueue_script( 'siema-js' );
  wp_enqueue_script( 'siema-init-js' );
  return $field;
}
?>