JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css">
<script src="https://code.jquery.com/jquery-2.2.4.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script>
<select id="selectNames">
<option></option>
<option value="1">Miguel</option>
<option value="2">Alexandre José</option>
<option value="3">Sara</option>
</select>


<div id="myModal" class="modal fade" role="dialog">
              <div class="modal-dialog">

                <form action="enviar.php" method="post">

                    <!-- Modal content-->
                    <div class="modal-content">
                      <div class="modal-header">
                        <button type="button" class="close" data-dismiss="modal">&times;</button>
                        <h4 class="modal-title">Cadastrar Nova Entrada</h4>
                      </div>
                      <div class="modal-body">
                        <p>Nome Pessoa</p>
                        <input type="text" name="nomePessoa" id="nomePessoa" value="">
                      </div>
                      <div class="modal-footer">
                        <button type="submit" class="btn btn-success" >Save</button>
                        <button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
                      </div>
                    </div>

                </form>


              </div>
            </div>

JavaScript

$('#selectNames').on('change', function() {
  $('#myModal #nomePessoa').val($(this).find('option:selected').text());
  $('#myModal').modal('show');
});