functions.php

<?php
add_action('wp_ajax_twitter_share', 'twitter_share', 0);
add_action('wp_ajax_nopriv_twitter_share', 'twitter_share');

function twitter_share() {
    $your_data = $_POST['your_data'];
    echo $your_data;
    die;
}

share.php

 <a href="https://twitter.com/intent/tweet?text=<?php the_title();?>&amp;url=<?php the_permalink();?>" data-lang="en" class="twitter-btn btn twitter-share" your_data="Your Custom Data">Tweet</a>

<script>
/******Twitter share start****/
window.twttr = (function (d, s, id) {
    var t, js, fjs = d.getElementsByTagName(s)[0];
    if (d.getElementById(id)) return; js = d.createElement(s); js.id = id;
    js.src = "//platform.twitter.com/widgets.js"; fjs.parentNode.insertBefore(js, fjs);
    return window.twttr || (t = { _e: [], ready: function (f) { t._e.push(f) } });
}(document, "script", "twitter-wjs"));
twttr.ready(function (twttr) {
        twttr.events.bind('tweet', function (event) {
            var yourData = event.target.attributes.your_data.value;
            jQuery.ajax({
   					type: 'POST',
   					url: "<?php echo admin_url('admin-ajax.php'); ?>",
   					data: {
   						action: "twitter_share",
   						your_data: yourData
   					},
   					success: function(result) {
   						console.log(result)
   					}
   			});
        });
     
});
/******Twitter share end******/
</script>