How to use cronbach alpha to check the internal validity of the first dimension?

Question

I have this example dataset that I applied MCA as follows

library("FactoMineR")
library("factoextra")

data(poison)

poison.active <- poison[1:55, 5:15]

res.mca <- MCA(poison.active, graph = FALSE)

The graph

I want to use cronbach alpha to check the internal validity of the first dimension. I know how to do it using PCA but it is not working with MCA as the variables are categorical.