Hi,
Do you mean that you want to combine values from multiple fields into one value in one field? Say you have field A and field B.
A B
45 66
56 77
67 88
Do you want to create a new field C which would have something like this:
A B C
45 66 "45/66"
56 77 "56/77"
67 88 "67/88"
?
Or you mean that you have used various symbols for various features (I guess based on some attribute) and now you want to calculate a new field which would have values based on the symbol used for this feature (green circle will be "123" and black square will be "456")? In this case, you do not have to bother with symbols at all since the symbology in ArcMap is always attribute-driven. This is because you have to differentiate features based on their properties (it could either non-spatial attributes (properties) or geometrical properties like area, length, etc.)