How to restrict a VBA text box to accept letters only

I have textBox on a VBA form named txtAnswer

I would like to restrict what can be entered in a VBA TextBox (txtAnswer) to letters only.
If the user presses a number key the number will not be typed into the TextBox but instead a Message Box will pop up showing the number key that has been pressed. Also if the user presses the Enter Key a Message Box should pop up saying “You pressed Enter Key”

So if the user starts typing “ a p p p l e  “ then the word “apple” will get typed into txtAnswer, but if the user presses a number key such 3 then the text in the txtAnswer will remain unchanged but a message box will pop saying “You pressed 3 ‘“
Thank you for your help.