How to change selected item text in list box at run time?

I tried with code like this:

Private Sub TextBox1_Leave(sender As Object, e As EventArgs) Handles MyBase.Leave
  ' This way is not working
  ListBox1.SelectedItem = TextBox1.Text
  ' This is not working too
  ListBox1.Items(ListBox1.SelectedIndex) = TextBox1.Text
End Sub

The form is looked like this:

I need to change that list text while user typing in the text box. Is it possible to do that at run time?

You are using the form's leave event MyBase.Leave, so when it fires, it is useless to you.

Try using the TextChanged event of the TextBox instead.

Private Sub TextBox1_TextChanged(sender As Object, e As EventArgs) _
                                 Handles TextBox1.TextChanged

Make sure to check if an item is actually selected in the ListBox:

If ListBox1.SelectedIndex > -1 Then
  ListBox1.Items(ListBox1.SelectedIndex) = TextBox1.Text
End If