Loop increase number

You can add a php variable and increment it every time the while loop runs

$args = array(
  'post_type' => 'events',
  'order' => 'ASC',
);
$wp_query = new WP_Query($args);
?>

<script type="application/ld+json">
    {
      "@context":"http://schema.org",
      "@type":"ItemList",
      "itemListElement":[
      <?php 
        $i=0;
        while ( have_posts() ) : the_post();
        $i++; ?>
        {
          "@type":"ListItem",
          "position":"<?php echo $i; ?>",
          "url":"<?php the_permalink(); ?>"
        },
      <?php endwhile; ?>
      ]
    }
</script>