The unit of the capacitance is Farad, abbreviated, as F. But F is usually too big to use in electronics, so the micro F, F and pico F, pF are often used. 1 F=0.000001 F, and  1 pF = 0.000001 F.

The capacitance of a capacitor is indicated as a value in F or in pF. The number in pF is usually too long, so a 3-digits annotation is used. The first two digits represent a two-digit number, and the third digit is the number of zeros to be added after the two-digit number. The list of the capacitors used in the Tube Mic DIY kit are:

Symbol
Value on the Schematics
Numbers on the Capacitor

C1
1/400V 400V,  1
C2
1/400V 400V,  1
C3
0.022/630V 223 ( = 22 000pF = 0.022 F)
C4
1000P/630V
630V, 1000PF

C5
0.022/630V 223 ( = 22 000pF = 0.022 F)
C6
100/25V 25V,  100F
C7
0.1/63V 104 ( = 100 000pF = 0.1 F)
C8
1/250V 400V,  1
C9
0.1/63V 104 ( = 100 000pF = 0.1 F)
C10
0.1/63V 104 ( = 100 000pF = 0.1 F)
C11
1000/10V 10V,  1000
CF
Not shown
2.5 ( = 2.5pF)





You may see each capacitor has a voltage value, which is shown on some capacitors, but is not on others. Either shown or not, this parameter is a very important one. This is the highest DC voltage under which the capacitor is allowed to work properly. If you put a capacitor with a low voltage in a place on PCB with a higher voltage, the capacitor will mostly be damaged.