I'm behind the NAT of my ISP. I'm in the private IP pool of my ISP then to public
IP. So I'm using shared public IP. How can I make dynamic DNS service work in my case?

i don't think you can do anything with a shared public IP.

One option for you to connect to your internal network is by using VPN. As others mentioned having a shared public IP means, you don't have control over inbound traffic routing(port forwarding) so its not possible to run services which can be accessed from outside the private network.