point = '\u2022'

this is there you want the bullet to show.
e.g

from tkinter import *
tk = tkinter.TK()

lists = ['python', 'c', 'c++']
list_box = Listbox(tk, bg, fg, font,)
list_box.pack()

for list in lists:
    list_box.insert(END, f'\u2022 {list}'