First Step :
1. Register to free DDNS provider , in this case I use noip.com.
2. Get into noip.com website, register your name, choose free DNS and follow all instructions. 
3. After that try to login to Mikrotik through Winbox use your free DNS.
4. If successfully, that is mean you have finished first step, and now going to second step.
Second Step :
1. Create script with the name no-ip_ddns_update in menu System –> Script. That script should has privileges to Read, Test, Write.
2. Copy and Paste this script to your Source field :
# No-IP automatic Dynamic DNS update
#--------------- Change Values in this section to match your setup ------------------
# No-IP User account info
:local noipuser "your_no-ip_user"
:local noippass "your_no-ip_pass"
# Set the hostname or label of network to be updated.
# Hostnames with spaces are unsupported. Replace the value in the quotations below with your host names.
# To specify multiple hosts, separate them with commas.
:local noiphost "hostname.no-ip.net"
# Change to the name of interface that gets the dynamic IP address
:local inetinterface "your_external_interface"
#------------------------------------------------------------------------------------
# No more changes need
:global previousIP
:if ([/interface get $inetinterface value-name=running]) do={
# Get the current IP on the interface
:local currentIP [/ip address get [find interface="$inetinterface" disabled=no] address]
# Strip the net mask off the IP address
:for i from=( [:len $currentIP] - 1) to=0 do={
:if ( [:pick $currentIP $i] = "/") do={
:set currentIP [:pick $currentIP 0 $i]
}
}
:if ($currentIP != $previousIP) do={
:log info "No-IP: Current IP $currentIP is not equal to previous IP, update needed"
:set previousIP $currentIP
# The update URL. Note the "\3F" is hex for question mark (?). Required since ? is a special character in commands.
:local url "http://dynupdate.no-ip.com/nic/update\3Fmyip=$currentIP"
:local noiphostarray
:set noiphostarray [:toarray $noiphost]
:foreach host in=$noiphostarray do={
:log info "No-IP: Sending update for $host"
/tool fetch url=($url . "&hostname=$host") user=$noipuser password=$noippass mode=http dst-path=("no-ip_ddns_update-" . $host . ".txt")
:log info "No-IP: Host $host updated on No-IP with IP $currentIP"
}
} else={
:log info "No-IP: Previous IP $previousIP is equal to current IP, no update needed"
}
} else={
:log info "No-IP: $inetinterface is not currently running, so therefore will not update."
3. Based on script above, attention to this script :
:local noipuser “your_no-ip_user”
:local noippass “your_no-ip_pass”
:local noiphost “hostname.no-ip.net”
:local inetinterface “your_external_interface”
Edit that script accord with your Mikrotik network and noip.com account. See script documentation here.
4. Finally the last action, we created a scheduler in the menu System-> Scheduler which will run the script every 5 minutes . Public ip information will be sent to NoIP.com every 30 minutes , so , although the public ip changed , we still can control remotely via a router that has been provided by NoIP.com .
