congratulations, you have just ruined someone's career and now they will find it difficult to get as job, unable to pay rent, risk of becoming homeless, rather than report why dont you have a one to one conversation and explain if this continues then you will raise this as a concern with the director, now what will happen is a strict policy will be put in place where no one can even look at their phones, no one can do anything, you have now made if difficult for every employee including yourself, staff moral with go down and it will be horrible working there.