res = Model._meta.get_field('test_field').verbose_name
res returns  'Test Field'

res = Model._meta.get_field('test_field').name
res returns 'test_field'

res = Model._meta.get_field('Test Field').name

{field.verbose_name: field for field in model._meta._fields()}['Test Field']

def get_field_from_verbose(meta, verbose_name):
    try:
        return next(f for f in _meta.get_fields() if f.verbose_name == verbose_name)
    except:
        raise KeyError(verbose_name)

get_field_from_verbose(Model._meta, 'Test Field')

<input type="checkbox" name="sel_fields[]" value="fieldname1">Verbose fieldname 1<br>
<input type="checkbox" name="sel_fields[]" value="fieldname2">Verbose fieldname 2<br>
<input type="checkbox" name="sel_fields[]" value="fieldname3">Verbose fieldname 3<br>