Hi,

you can open loop-item.php and replace

<div class="item">
        <figure class="item-thumb">
            <a class="item-zoom" data-rel="prettyPhoto[gal]" href="<?php echo ci_get_image_src( get_the_ID(), 'large' ); ?>">
                <img src="<?php echo ci_get_image_src( get_the_ID(), 'ci_thumb' ); ?>">
                <div class="overlay"><i class="fa fa-search-plus"></i></div>
            </a>
        </figure>
    </div>

with

<div class="item">
        <figure class="item-thumb">
            <a class="item-zoom" data-rel="prettyPhoto[gal]" title="<?php echo wp_get_attachment_caption(get_the_ID())?>" href="<?php echo ci_get_image_src( get_the_ID(), 'large' ); ?>">
                <img title="<?php echo wp_get_attachment_caption(get_the_ID())?>" src="<?php echo ci_get_image_src( get_the_ID(), 'ci_thumb' ); ?>">
                <div class="overlay"><i class="fa fa-search-plus"></i></div>
            </a>
        </figure>
    </div>

then open scripts.js and replace

$pp.prettyPhoto({
            show_title: false,

with

$pp.prettyPhoto({
            show_title: true,

Open the default editor and then navigate to the /themes/mykonos/ and /themes/mykonos/js/  folder to find the file.

Let me know if you need additional help on this.