add.ctp

<?php
echo $this->Form->create($applicant);

echo $this->Form->input('first_name');
echo $this->Form->input('surname');

echo $this->Form->input('applicant_subjects.0.subject_id');
echo $this->Form->input('applicant_subjects.0.description');
echo $this->Form->input('applicant_subjects.1.subject_id');
echo $this->Form->input('applicant_subjects.1.description');

echo $this->Form->submit();
echo $this->Form->end();

ApplicantsController.php

<?php
	public function add() {
		$applicant = $this->Applicants->newEntity($this->request->data);

		debug($applicant);

		$subjects = $this->Applicants->ApplicantSubjects->Subjects->find('list');
		$this->set('subjects', $subjects);
		$this->set('applicant', $applicant);
	}

gistfile1.txt

object(HesaMbit\Model\Entity\Applicant) {

	'new' => true,
	'accessible' => [
		'*' => true
	],
	'properties' => [
		'first_name' => 'My test guy',
		'surname' => 'surname for him',
		'applicant_subjects' => [
			(int) 0 => object(HesaMbit\Model\Entity\ApplicantSubject) {

				'new' => true,
				'accessible' => [
					'*' => true
				],
				'properties' => [
					'subject_id' => 'anmu',
					'description' => 'Subject description'
				],
				'dirty' => [
					'subject_id' => true,
					'description' => true
				],
				'original' => [],
				'virtual' => [],
				'errors' => [],
				'repository' => 'ApplicantSubjects'
			
			},
			(int) 1 => object(HesaMbit\Model\Entity\ApplicantSubject) {

				'new' => true,
				'accessible' => [
					'*' => true
				],
				'properties' => [
					'subject_id' => 'amn',
					'description' => 'Subject 2 description'
				],
				'dirty' => [
					'subject_id' => true,
					'description' => true
				],
				'original' => [],
				'virtual' => [],
				'errors' => [],
				'repository' => 'ApplicantSubjects'
			
			}
		]
	],
	'dirty' => [
		'first_name' => true,
		'surname' => true,
		'applicant_subjects' => true
	],
	'original' => [],
	'virtual' => [
		(int) 0 => 'full_name',
		(int) 1 => 'formatted_date_of_birth'
	],
	'errors' => [],
	'repository' => 'Applicants'

}