Hello,
If you don't have a multimeter with capacitance measurement capability, you can use a big resistor and a switch. You charge the capacitor to a certain voltage E, and with your clock in hand, you open the switch so it can discharge through the big resistor with a time constant RC that is big enough to be able to measure the time at which the capacitor voltage is E/2.
You use the discharge equation to get C.
Of course, that's kind of a Scorched Earth approach, but still .. Better than absolutely nothing.