Using Tkinter in Jupyter Notebook

Your code is working just fine. Nevertheless for those using python3 module name has changed from Tkinter to tkinter all in lowercase. Edit the name and you're good to go!

In a nutshell.

python2:

from Tkinter import *

python3:

from tkinter import *

Look at the screenshot below

from Tkinter import *

def printData(firstName, lastName):
    print(firstName)
    print(lastName)
    root.destroy()

def get_input():

    firstName = entry1.get()
    lastName = entry2.get()
    printData(firstName, lastName)


root = Tk()
#Label 1
label1 = Label(root,text = 'First Name')
label1.pack()
label1.config(justify = CENTER)

entry1 = Entry(root, width = 30)
entry1.pack()

label3 = Label(root, text="Last Name")
label3.pack()
label1.config(justify = CENTER)

entry2 = Entry(root, width = 30)
entry2.pack()

button1 = Button(root, text = 'submit')
button1.pack() 
button1.config(command = get_input)

root.mainloop()

Copy paste the above code into a editor, save it and run using the command,

python sample.py

Note: The above code is very vague. Have written it in that way for you to understand.