The easist way is to measure with calipers then counting the amount off fat from the results.
You can also use a electric counter that stream some electricity though your muscles, it will give results because muscles and fat have different resistances.
Then the final way I know off is to measure BF in water. I do not know how but someone else can probably tell.
To keep track off BF get a scale which count bf%, this is not accurate but it's good to use to see the progress.