To get started with post-processing outputs, you may find the information in Chapter 8 of the users guide helpful.
In particular, the combine program released as part of the CMAQ code repository allows you to aggregate individual variables in raw model output files into variables of interest. To do so, you will have to create custom SpecDef species definition files that define the aggregations you would like to perform. Previous discussions (here and here) on using combine to post-process CMAQ ISAM outputs may be helpful.
Based on the sensinput file you posted, the sensitivity parameter you define as EMISNVOC would track the sensitivity of all model species to FORM emissions, not the sensitivity of FORM to VOC emissions. If you want to calculate sensitivity to VOC emissions, you will have to list all of the relevant emitted species in the line after the “SPECIES” entry, as discussed in my previous post.
Finally, as discussed in the DDM-3D user guide chapter I linked to in one of my earlier responses in the other thread, the sensitivity parameter name should only be 3 characters long, not 8 as in your definition of “EMISNVOC”. The reason is that the variables in the ASENS output file will be combination of model species names and sensitivity parameter name, separated by an underscore. Since the total variable length is limited to 16 and the names of some model species can be fairly long, defining a sensitivity parameter name with more than 3 characters can cause problems.