difference = {}

for session_id in data2.SESSION.unique():
    df = dict_name_pd['BEHAVIOSEC_header']
    time, eventTime = map(int, df[df['SESSION'] == session_id].time.iloc[0].split(' '))
    difference[session_id] = (time - eventTime // 1000) * 1_000_000_000
    
data2['eventTimeHardware'] = data2.apply(lambda x: difference[x.SESSION] + x.eventTime, axis=1)