JSFiddle - React, Tailwind, and code Playground

HTML

<div id="button_box"><h2>Hover This</h2>
    <div id="form_box">
        <form action="#" method="post">
            <select id="select_option" onChange="Javascript:doSomething();">
                <option value="a">Value A</option>
                <option value="a">Value B</option>
                <option value="a">Value C</option>
                <option value="a">Value D</option>
                <option value="a">Value E</option>
            </select>
        </form>               
    </div>
</div>

CSS

#button_box { display:block; width: 150px; height: 75px; position:relative; background: #ddd; }

#button_box h2 { text-align: center }

#button_box #form_box { display: none; position:relative; top: 51px; width: 150px; background: #ccc }

#button_box:hover #form_box { display:block }

#form_box select { background: #bbb }