as commented by acw1668.
separatedWord = list(input_word)
you can typecast a string as list
try this code:
from tkinter import *
class MyEntry(Entry):
    def __init__(self, root, textvariable):
        Entry.__init__(self, master=root, textvariable=textvariable)
        #binding your trace handler to your textvariable
        textvariable.trace_add("write", self._traceHandler)
    #or just use this handler
    def _traceHandler(self, x, y, z):
        # code block
        print(self.getSeparatedWord())
    #you can call this
    def getSeparatedWord(self):
        value = self.get()
        return list(value)
root = Tk()
my_textvar = StringVar()
my_entry = MyEntry(root, my_textvar)
my_entry.pack()
root.mainloop()