Make ListBox items have a different value than item text

I want a ListBox full of items. Although, each item should have a different value. So when the user selects an item and presses a button, a method will be called which will use the value the select item has.

I don't want to reveal the item values to the user.

EDIT: This is not for ASP.NET, it's for a Windows Forms application. I just thought the HTML example would be easy to read.

I have the inspiration from HTML:

<form>
<input type="radio" name="sex" value="Value1" /> Male
<br />
<input type="radio" name="sex" value="Value2" /> Female
</form>

This also allows me to use different values than what the user sees.