[Python] Get input in Python tkinter Entry when Button pressed

I am trying to make a 'guess the number' game with Pyhon tkinter but so far I have not been able to retrieve the input from the user.

How can I get the input in entry when b1 is pressed?

I also want to display a lower or higher message as a clue to the player but I am not sure if what I have is right:

import time
import random
import decimal
import tkinter as tk

root = tk.Tk()

randomnum = float(decimal.Decimal(random.randrange(100,10000))/100)
guess = 0

def get(entry):
guess = entry.get()
return guess

def main():
b1 = tk.Button(root, text="Guess", command=get)
entry = tk.Entry()
b1.grid(column=1, row=0)
entry.grid(column=0, row=0)
root.mainloop()
print(guess)
if guess < randomnum:
l2 = tk.Label(root, text="Higher!")
l2.grid(column=0, row=2)
elif guess > randomnum:
l3 = tk.Label(root, text="Lower!")
l3.grid(column=0, row=2)


while guess != randomnum:
main()
l4 = tk.Label(root, text="Well guessed")
time.sleep(10)

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