Conditional Enqueueing of scripts in WordPress

shortcode.php

<?php

add_action('wp_enqueue_scripts', 'enqueue_if_shortcode');

function enqueue_if_shortcode(){
  global $post;

  if ( $post && has_shortcode( $post->post_content, 'your_shortcode_tag' ) {
    // Enqueue
  }
}

widget.php

<?php

add_action('wp_enqueue_scripts', 'enqueue_if_widget');

function enqueue_if_widget(){
  // widget base id in https://codex.wordpress.org/Widgets_API#Default_Usage is 'my_widget'
  // check https://developer.wordpress.org/reference/functions/is_active_widget/ for more info
  
  if ( is_active_widget(false, false, 'your_widget_base_id', true) ) {
       // enqueue your scripts;
    }  
}