Customize Woocommerce Checkout form

On the woocommerce checkout form i need to add two fields.

School (dropdown list)
Branch (dropdown list)
When user selects School, specific branches related to that school should show up in dropdown. It’s similar to country field, once user selects country, state shows up.

Can you please let me know how i can customize woocommerce checkout form to implement this requirement or if there any free or paid plugins available to achieve this requirement