JSFiddle - React, Tailwind, and code Playground

HTML

<select name="periodo"  style="width:260px" onchange="setValues(this)" > 
    <option value="0">Elige una opción</option> 
    <option value="1">Prueba</option>
</select>
<input  type="text"  name="pescolar" id="pescolar"  value="" />

JavaScript

function setValues(select){
    var text = select.options[select.selectedIndex].text,
        id = select.value;
    document.getElementById('pescolar').value = text + " " +id;
}