Try something like this, first 2 lines are used to generate sample data only.
| makeresults
| eval _raw="{\"disk\": [{\"capacity\": \"12874416128\", \"diskPath\": \"/\", \"freeSpace\": \"12790087680\"}, {\"capacity\": \"7505707008\", \"diskPath\": \"/usr\", \"freeSpace\": \"3691720704\"}, {\"capacity\": \"1063256064\", \"diskPath\": \"/boot\", \"freeSpace\": \"825552896\"}, {\"capacity\": \"42392092672\", \"diskPath\": \"/logs\", \"freeSpace\": \"41320570880\"}, {\"capacity\": \"21250441216\", \"diskPath\": \"/shBC\", \"freeSpace\": \"2040201216\"}, {\"capacity\": \"7505707008\", \"diskPath\": \"/home\", \"freeSpace\": \"7430582272\"}, {\"capacity\": \"4284481536\", \"diskPath\": \"/tmp\", \"freeSpace\": \"4196638720\"}, {\"capacity\": \"10622074880\", \"diskPath\": \"/logarch\", \"freeSpace\": \"10588340224\"}, {\"capacity\": \"63319834624\", \"diskPath\": \"/apps\", \"freeSpace\": \"31894880256\"}, {\"capacity\": \"7505707008\", \"diskPath\": \"/var\", \"freeSpace\": \"5256704000\"}, {\"capacity\": \"7505707008\", \"diskPath\": \"/var/tmp\", \"freeSpace\": \"5256704000\"}]}"
| spath
| rename disk{}.capacity AS capacity, disk{}.diskPath AS path, disk{}.freeSpace AS space
| eval cap_path=mvzip(capacity,path)
| eval cap_path_space=mvzip(cap_path,space)
| mvexpand cap_path_space
| makemv delim="," cap_path_space
| eval capacity=mvindex(cap_path_space,0), path=mvindex(cap_path_space,1), space=mvindex(cap_path_space,2)
| fields - cap_path,cap_path_space
