192.168.1.100 looks like an internal IP. You'll need a couple things to be able to achieve this in a simple way:

1. An IP that can be reached from outside your Office Network.
2. A DNS name you can point to the IP reachable from outside your Office Network.

For the IP that can be reached from outside your Office Network you most likely have already an static one from your ISP assuming you have a corporate internet service, otherwise you have a dynamic IP if you use a domestic Internet Service. Once you figure out what's your external IP address you need to open the Odoo Port on your modem/switch or whatever you use, from your post it seems like it is Port 8960, so go to your modem/router documentation and find how to do it, most likely will be under Advanced Settings or Firewall / Port Forwarding, in there you need to assign to your Internal IP the Odoo Port so it would look something like Internal Address: 192.168.1.100 and Port: 8960.

Now for DNS name you can point to the IP reachable from outside your Office Network, there's two options depending on the type of  your external IP. If you have an static one you can just point a DNS name of your choosing to your external IP and type that with the port or even just the IP, so if your external IP is lets say 108.8.8.8 you should be able at this point without messing with DNS to just type 108.8.8.8:8960 on the browser and access your Odoo instance, or do the Web Server conf files (Apache or nGinX) to open the service on port 8960 on the /Odoo location of www.mycompany.com which is much more compliacted, you could just do a simpler name like odoo.mycompany.com and just point that to 108.8.8.8 with minimal configuration on the Web Server. at this pint you should be able to test it by just editing your system host file and adding IP 108.8.8.8 for the name odoo.company.com. If you IP is Dynamic you'll need a Dynamic DNS service like iWesabe suggested (No-IP is a good place to start) and point it but not to your internal IP, point it to your External IP.

Hope this helps.