How to add subcategories for listing field?

In my country, there are districts in each city.
I have set my city a drop down menu. What I want to add is another sub drop down list when you choose a specific city.
For example: there are city a, b, c and each city has different districts like: a1, a2, a3, ba, bb, bc, and c11, c12, c13

So when you list a product, I want them to choose city from the drop down. If they choose city a, then another drop down show up as: a1, a2, a3.
For if they pick city b, another drop down follow as: ba, bb, bc.

This is the best way to make it so ppl can find the ads near the place they are able to go.

Is this possible to do?

Thank you

Hello Yung Yang,

Please try to install multifield plugin and configure it.

Thank you.
I will try it out.