create two hidden form fields to capture the labels, then use javascvript to populate the hidden form fields with the labels on change. here is an example:
<form name="form1" method="post" action="">
<label for="select"></label>
<select name="select" id="select" onChange="document.form1.hiddenField.value = document.form1.select[document.form1.select.selectedIndex].text">
<option value="1">one</option>
<option value="2">two</option>
<option value="3">three</option>
<option value="4">four</option>
</select>
<input type="hidden" name="hiddenField" id="hiddenField">
<label for="button"></label>
<br>
<input type="submit" name="button" id="button" value="Submit">
<br>
List value = <?php echo((isset($_POST["select"]))?$_POST["select"]:"") ?>
<br>
Hidden Field Value=<?php echo((isset($_POST["hiddenField"]))?$_POST["hiddenField"]:"") ?>
</form>