Sending a Javascript Variable to Flask Python Code without Form-Event

I have a problem with Flask and Javascript. I want to use a website to control a minirobot with joysticks. I have found nippleJS (https://github.com/yoannmoinet/nipplejs) and included it to my website. I can print the joystick values to the web console, but i need those values at my pythonscript for the robot control. Can anybody help me please? Here is my code: HTML:

<script src="{{url_for('static', filename='nippleJS.js')}}"></script>
    <script>
        var joystickL = nipplejs.create({
            zone: document.getElementById('left'),
            mode: 'static',
            position: { left: '20%', top: '50%' },
            color: 'green',
            size: 200
            
        });
        

        var joystickR = nipplejs.create({
            zone: document.getElementById('right'),
            mode: 'static',
            position: { left: '80%', top: '50%' },
            color: 'red',
            size: 200,
            lockY: 1
        });

        joystickL.on('move', function (evt, nipple) {
            var dis = nipple.distance;
            var angle = nipple.angle.radian;
            var pos = nipple.position;
            console.log(dis);
            console.log(angle); </script>

And here is my Flask Code:

from flask import Flask, render_template, request, redirect, url_for, jsonify

app = Flask(__name__)

@app.route("/", methods=['GET', 'POST'])
def home():

if request.method == 'POST':
    
    if request.form['btn'] == 'Demo Programme':
        return redirect(url_for('demo'))

    elif request.form['btn'] == 'Manuelle Steuerung':
        return redirect(url_for('steuerung'))

    elif request.form['btn'] == 'Erweiterte Optionen':
        return redirect(url_for('optionen'))



return render_template('home.html')