import arcpy
feature_class = 'C:data.gdbfeatures123' #Change
field_to_update = 'somefield' #Change
values = [1,2,3,4] #Change

list_iterator = iter(values)

with arcpy.da.UpdateCursor(feature_class, field_to_update) as cursor:
    for row in cursor:
        try:
            row[0] = next(list_iterator) #Assign list value to row[0]/field_to_update
            cursor.updateRow(row) #Update the field
        except StopIteration: #If you have less items in list than number of rows in feature class
            print 'List is empty, cant update any more rows'