from tkinter import *

def Del(a):
    print(a)

root = Tk()
frame = Frame(root)
scrollbar = Scrollbar(frame)
scrollbar.pack(side=RIGHT, fill=Y)
listbox = Listbox(frame, yscrollcommand=scrollbar.set, width=35, height=16, font="arial 11", selectmode=SINGLE)
for i in range(100):
    listbox.insert(END, str(i))
listbox.pack(side=TOP, fill=BOTH)
scrollbar.config(command=listbox.yview)
frame.grid(row=0, column=0)
Button(root, text=" Del ", font="arial 11").grid(row=1, column=0, padx=10, pady=10)
mainloop()

 Button(root, text=" Del ", font="arial 11", command=lambda: Del(listbox.selection_get())).grid(row=1, column=0, padx=10, pady=10)

 listbox.activate(pos0)
listbox.select_set(pos0)
listbox.see(pos0)