recaptcha_form.html

<div class="" id="modal-form">
    <h2>Login</h2>
    <form method="POST" class="mx-auto" action="{% url 'login' %} ">
        {% csrf_token %}

        {% for field in form %}
            <div class="form-group">
                {{ field }}
                {% if field.help_text %}
                <small class="form-text text-muted">{{ field.help_text|safe }}</small>
                {% endif %}
                <small class="form-text">{{ field.errors }}</small>
            </div>
        {% endfor %}

        {{ form.non_field_errors }}

        <div class="g-recaptcha" data-sitekey="<your_site_key>"></div>
        <button type="submit" class="btn btn-primary">Submit</button>
    </form>
</div>

{% block scripts %}
    <script src='https://www.google.com/recaptcha/api.js'></script>
{% endblock %}