Use a "intern personnal captcha"
Exemple: Add 2 labels. Add a TextBox.
Under the Public Class add:
Dim RandomNumber As New Random
On the Form Startup, write:
Label1.Text = RandomNumber.Next(1, 20).ToString() 'Captcha with numbers( 1 to 20)
Label2.Text = RandomNumber.Next(1, 20).ToString()
On the account creation button, write:
If TextBox1.Text = Val(Label1.Text) + Val(Label2.Text) Then '+ for addition, - for substraction, / to divide and * to multiplicate.
MsgBox("Captcha Correct")
Else
MsgBox("Captcha Incorrect")
Label1.Text = RandomNumber.Next(1, 20).ToString() 'Captcha with numbers( 1 to 20)
Label2.Text = RandomNumber.Next(1, 20).ToString()
End if
Good luck !