Lay Theme Forum

I have solved this request by myself but if someone is interested, here is the code I used.

Custom CSS

body {
    position: relative;
}
#buttonCta {
    position: fixed;
    z-index: 999;
    border-radius: 70px;
    background-color: #0000FF;
    border: 5px solid #F0FCD2;
    text-align: center;
    padding: 12px 25px;
    cursor: move;
}

#buttonCta     a {
    
        font-family: SpaceMono-Regular;
        color: #F0FCD2;
        text-align: center;
        text-transform: uppercase;
        font-size: 60px;
        cursor: pointer;
 }
 
#buttonCta:hover {
        background-color: #F0FCD2;
        border: 5px solid #0000FF;
    }

    
    #buttonCta:hover a {
        color: #0000FF;
    }

 @media only screen and (max-width: 601px) {
       #buttonCta {
        display: none;
       }
    }

CUSTOM HEAD CONTENT (JAVASCRIPT)

<script type="text/javascript">
document.addEventListener('DOMContentLoaded', () => {
const cta = document.getElementById("buttonCta");

if((window.innerWidth > 601) && cta) {
    var randomtop = Math.floor(Math.random() * 70);
    var randomleft = Math.floor(Math.random() * 70);
    cta.style.top = `${randomtop}vh`;
    cta.style.left = `${randomleft}vw`;
    dragElement(cta);
}

console.log(window.innerWidth > 601, cta)

function dragElement(elmnt) {
  var pos1 = 0, pos2 = 0, pos3 = 0, pos4 = 0;

    elmnt.onmousedown = dragMouseDown;

  function dragMouseDown(e) {
    e = e || window.event;
    e.preventDefault();
    // get the mouse cursor position at startup:
    pos3 = e.clientX;
    pos4 = e.clientY;
    document.onmouseup = closeDragElement;
    // call a function whenever the cursor moves:
    document.onmousemove = elementDrag;
  }

  function elementDrag(e) {
    e = e || window.event;
    e.preventDefault();
    // calculate the new cursor position:
    pos1 = pos3 - e.clientX;
    pos2 = pos4 - e.clientY;
    pos3 = e.clientX;
    pos4 = e.clientY;
    // set the element's new position:
    elmnt.style.top = (elmnt.offsetTop - pos2) + "px";
    elmnt.style.left = (elmnt.offsetLeft - pos1) + "px";
  }

  function closeDragElement() {
    /* stop moving when mouse button is released:*/
    document.onmouseup = null;
    document.onmousemove = null;
  }
}
});
</script>

CUSTOM HTML TOP

<div id="buttonCta">
    <a href="LINK">TEXT ON THE BUTTON</a>
</div>