Random Number Generator - Store generated numbers

[Noob script kiddie]

Right so my generator is working, but I now want to take the numbers that it generates and add them to a list of generated numbers. So you can monitor what numbers have been generated.

Then ideally a way to exclude these numbers from being generated again.

Heres my code for my generate button

Dim Low As Integer = 1
        Dim High As Integer
        High = HighNum.Text
        Low = TextBox2.Text
        Get_Random(Low, High)
        TextBox1.Visible = True
        Beep()

And my Random Number code

Sub Get_Random(ByVal Low As Integer, ByVal High As Integer)
 
        TextBox1.Text = Math.Floor((High - Low + 1) * Rnd() + Low)
 
    End Sub

Can I then somehow work in a, if number is in listbox regenerate?