GNU/Linux, unlike MacOSx, uses the /proc directory structure, a.k.a. procfs, to store system data. The arp cache is located at /proc/net/arp You print the data to stdout directly from that system file via:

cat /proc/net/arp

I realized that you may also want the memory address that the kernel uses to find the arp cache. The exact address may vary. However, you can find the memory address table for all arp memory addresses the kernel uses in /proc/kallsyms

cat /proc/kallsyms |grep arp_

May be helpful as well.