I did some searching and came up with no script for namecheap.coms dynamic dns service, can any one point me in the right direction. 
I know this is an old topic, but I figured I would update it in case anyone else was looking for the info. Hereās a script that I came up with to update your dynamic DNS addresses on Namecheap.
# Set local variables. If you want to update subdomain.example.com, put in "subdomain" under subdomain and "example.com" in the domain variable. If you want to update just example.com with no subdomain, enter in "@" for the subdomain.
:local password "password"
:local subdomain "subdomain"
:local domain "example.com"
# Get Public IP
/tool fetch url="http://bot.whatismyipaddress.com/" mode=http dst-path=pubIP.txt
:local currentIP [/file get pubIP.txt contents]
:log info "Current Public IP is:$currentIP"
:local url1 "http://dynamicdns.park-your-domain.com/update\3Fhost=$subdomain&domain=$domain&password=$password&ip=$currentIP"
/tool fetch url=($url1) mode=http
:log info "DNS Successfully Updated"
After spending 2 days searching for a working script to update my wan IP to Namecheap, I want to say this script is excellent. Short and precise.
thx a lot @mattsawatzky
Why not use the built-in feature in RouterOS ?
I use this for years now without any issues or need for 3e party services.
I use dynu and it works great, and it has the ability to assign a C-name, so I point my FREE service at the MT CLOUD.
Perhaps in Belgium you like to torture friends or businesses with a long ass winded name to use to reach servers :-PPP, but I prefer being human!! 
Well I have my own domain too and I have some CNAMEās pointing to the ālong ass winded nameā of my RB3011 
to make life slightly more enjoyable.
ooooh fancy, own domain nameā¦ I am just a peon using free dynu and free mt cloud.
Please send chocolate to keep us masses happy!!
Masses can have own domain names too, if they want, itās simple and cheap. I need to give up six beers each year to afford one, and itās that many only because beer is really cheap here, otherwise it would be even less (not that Iām complaining ). And it includes use of nameservers run by registrar, so no extra investment is needed. And unlike with some free dyndns provider, who lends you .theirdomain.tld and you never know when they can close the store and you lose it, this is yours as long as you pay those few dollars a year. And you get unlimited subdomains and complete freedom to do whatever you want with them.
Please point in the right direction good Sir, would like to sample some homegrownā¦ domain names.
I have some in mind.
sindy.is.god
eye.love.mkx
sob.sob.sob
Bad news, even though the list of available TLDs have grown significantly in recent years, neither of your choices exists so far. There are only these:
http://data.iana.org/TLD/tlds-alpha-by-domain.txt
But itās probably best to go with good old com/net/org/ anyway.
Ahh so dynu has some ranging from 8.99/yr org.uk to 29.99/ry .guru
I think I would take .link for 9.99/yr
stink.my.link
fix.my.link
suck.my.link
are all early contendersā¦
hmmmm
ros7.wireguard.link
my.home.link
.rocks is 11.99
normis.rocks ( if he sent me a wireless wire pair, I would do it )
yeah .ca is 14.99 though hard to justify spending an xtra $5 LOL