Are you buying bulk oil? Capsules are easier, but I strongly suggest buying flax seed whole and grinding it up. You retain the natural fibers, not to mention the oddball rumors that refined flax seed oil might cause cancer? Sounds weird, but why risk is and why not just go for the whole seed, right?
If you use the whole seed, just use a measuring spoon. And FYI, if you continue to use oil, you could always convert the ml to something useable.
http://www.convertunits.com/from/ml/to/oz