<form action="">
  <input type="email" placeholder="Email">
  <button type="submit">&#10004;</button>
</form>

form {
  display: flex;
}
input,
button {
  padding: 10px 15px;
  border: 1px solid #000;
  border-radius: 0px;
}
button {
  border-left: 0px;
  background: #000;
  color: #fff;
}
form *:focus {
  outline: none;
}