TextBox have property PasswordChar, so you just choose symbol to be displayed while typing password in this TextBox. Perhaps much more easy than using InputBox.
Now you work with InputBox, so you read user input like:
inputbox_text = InputBox()
If you want to use Textbox so make UserForm with textbox and use Textbox.Text to compare user input with defined password.
To show UserForm:
UserForm1.Show